June 2007 - Logic Game 3 Setup

Video Transcript:

0:03
So, the third game of the June 2007 LSAT states: A cruise line is scheduling 7
0:09
week-long voyages for the ship Freedom. Each voyage will occur in exactly one of
0:14
the first 7 weeks of the season
0:16
weeks 1 through 7. Each voyage will be to exactly one of four destinations: Jamaica,
0:22
Martinique, or Trinidad. Each destination will be scheduled for at
0:26
least one of the weeks the following conditions apply to freedom scheduled.
0:31
Alright, first place in what we already know. This is a seven-week schedule. So, we're going
0:37
to have seven weeks. And we have four destinations that are possible in
0:44
Guadalupe, Jamaica, Martinique, and Trinidad and we know that each of these
0:52
will be scheduled for at least one of the weeks. So, each of these shows up at
0:59
least once. Alright, so let's think about what that rule is telling us. Each destination
1:06
will be scheduled for at least one of the weeks and we have four destinations but
1:11
seven weeks which means there are three weeks that are open. So, let's think about the
1:18
possibilities for the numerical distribution of these destinations. So, if we
1:24
have three weeks that are open we can have one of the destinations appear four
1:29
times and the other three appear only once. We could also have one destination
1:34
appear three times and another twice and the other two once. And lastly we can have
1:42
three destinations appear twice and one destination appear one time. And again
1:48
that's coming directly from the rule. Each destination will be scheduled for
1:51
at least one of the weeks and the fact that we have weeks one through seven.
1:58
Alright, so now that we have a nice base let's turn our attention to the conditions that
2:02
are gonna apply to freedoms schedule. The first condition tells Jamaica will not
2:08
be the destination in week 4. So, we can write Jamaica is not going to be in week 4.
2:15
The second condition tells us Trinidad will be the destination in week seven. So,
2:20
we can add Trinidad to week seven. So, Trinidad is definitely going to be week 7
2:25
but keep in mind it's possible that Trinidad shows up again.
2:29
Ok. Turning our attention to the third condition. Freedom will make exactly two
2:35
voyages to Martinique at least one voyage to Guadalupe will occur in some week between
2:41
those two voyages. Alright, so the third rule here. What we're seeing is two voyages
2:51
exactly 2 to Martinique. So, you notice what that does right away is it eliminates
2:59
the 4-1-1 possibility in our numerical distribution because if Martinique is showing
3:05
up exactly twice in the 4-1-1 one possibility there is no one showing
3:11
exactly twice. So, that possibility has been eliminated now based on the third
3:16
condition. Again, the condition is that there is at least one trip to Guadalupe
3:23
inbetween the two trips to Martinique. So, we have that block.
3:33
Now, keep in mind we cannot make certain deductions here. For example, you cannot conclude
3:37
based on the fact that Trinidad is 7th that Martinique cannot appear 5th because again if Martinique appeared fifth
3:46
as long as the other Martinique appears third or earlier and Guadalupe is in between
3:53
and it's still fine. So, we can't do anything with that rule. Turning our
3:58
attention now to the fourth condition. Guadalupe will be its destination in the
4:04
week preceding any Voyage it makes to Jamaica. Alright, so it's really important to think carefully about
4:10
what this rule is saying because again we know 'any' introduces sufficient so any voyage it makes to
4:17
Jamaica
4:17
must be preceded by a trip to Guadalupe. And we know for sure there's going to be at least
4:28
one trip to Jamaica. Therefore we know for sure we are going to have to place this 'G' 'J'
4:39
box at least once in our schedule. Possibly twice but notice another
4:48
conclusion and we can me is that J can only show up max twice because if
4:58
Jamaica were to appear 3 times we would have to have Guadalupe in every week preceding
5:04
those which would be six destinations already
5:09
of the seven but we also have Martinique and Trinidad remaining to place so
5:16
that clearly would not work. So Jamaica can only appear maximum twice. And one last
5:24
Deduction we can make from rule number four is that Jamaica cannot be first
5:29
because of Jamaica was first we would not have a week preceding it for Guadalupe.
5:36
And now turning our attention to the fifth and final condition: No destination will be
5:41
scheduled for consecutive weeks. So, telling us that we can't have Guadalupe, Jamaica, Martinique,
5:49
or Trinidad in consecutive weeks and we know since we have Trinidad in
5:55
week 7 that we cannot see Trinidad again in week 6. And that is the set up for this
6:03
game. The only other thing that you should be aware of is the placement
6:08
possibilities for our Jamaica / Guadalupe block. Again, at this point only possibilities
6:14
are 1 and 2. We could also have that appear two and three and then four and five
6:24
and lastly 5 and 6 and keep in mind
6:28
have J show up twice so we could actually have two of those blocks in our
6:32
game so let's turn our attention now to the questions...